DETAILS OF DESIGN AND ENGINES OF F-35AIRCRFT

DESIGN:- OVERVIEW

The F-35 closely resembles a smaller, single engine Lockheed Martin F-22 Raptor, drawing design elements from its twin-engine sibling. The exhaust duct design was inspired by the General Dynamics Model 200, proposed for a 1972 supersonic VTOL fighter requirement for the Sea Control Ship.Although several experimental designs have been developed since the 1960s, such as the unsuccessful Rockwell XFV-12, the F-35B is to be the first operational supersonic, STOVL stealth fighter. Acquisition deputy to the assistant secretary of the Air Force, Lt. Gen. Mark D. "Shack" Shackelford has said that the F-35 is designed to be America's "premier surface-to-air missile killer and is uniquely equipped for this mission with cutting edge processing power, synthetic aperture radar integration techniques, and advanced target recognition". Lockheed Martin states the F-35 is intended to have close- and long-range air-to-air capability second only to that of the F-22 Raptor. Lockheed Martin has said that the F-35 has the advantage over the F-22 in basing flexibility and "advanced sensors and information fusion". Lockheed Martin has suggested that the F-35 could replace the USAF's F-15C/D fighters in the air superiority role and the F-15E Strike Eagle in the ground attack role. Some improvements over current-generation fighter aircraft are: Durable, low-maintenance stealth technology, using structural fiber mat instead of the high-maintenance coatings of legacy stealth platforms; Integrated avionics and sensor fusion that combine information from off- and on-board sensors to increase the pilot's situational awareness and improve target identification and weapon delivery, and to relay information quickly to other command and control (C2) nodes High speed data networking including IEEE 1394b and Fibre Channel. (Fibre Channel is also used on Boeing's Super Hornet.) The Autonomic Logistics Global Sustainment (ALGS), Autonomic Logistics Information System (ALIS), and Computerized maintenance management system (CMMS) are to help ensure aircraft uptime with minimal maintenance manpower. The Pentagon has moved to open up the competitive bidding by other companies. This was after Lockheed Martin stated that instead of costing twenty percent less than the F-16 per flight hour, the F-35 would actually cost twelve percent more. Though the ALGS is intended to reduce maintenance costs, the company disagrees with including the cost of this system in the aircraft ownership calculations. The USMC have implemented a workaround for a cyber vulnerability in the system. The ALIS system currently requires a shipping container load of servers to run, but Lockheed is working on a more portable version to support the Marines' expeditionary operations. Electro-hydrostatic actuators run by a power-by-wire flight-control system. A modern and updated flight simulator, which may be used for a greater fraction of pilot training in order to reduce the costly flight hours of the actual aircraft. Lightweight, powerful Lithium-ion batteries to provide power to run the control surfaces in an emergency. Structural composites in the F-35 are 35% of the airframe weight (up from 25% in the F-22). The majority of these are bismaleimide (BMI) and composite epoxy material. The F-35 will be the first mass-produced aircraft to include structural nanocomposites, namely carbon nanotube reinforced epoxy. Experience of the F-22's problems with corrosion led to the F-35 using a gap filler that causes less galvanic corrosion to the airframe's skin, designed with fewer gaps requiring filler and implementing better drainage. The relatively short 35-foot wingspan of the A and B variants is set by the F-35B's requirement to fit inside the Navy's current amphibious assault ship parking area and elevators; the F-35C's longer wing is considered to be more fuel efficient. A United States Navy study found that the F-35 will cost 30 to 40 percent more to maintain than current jet fighters; not accounting for inflation over the F-35's operational lifetime. A Pentagon study concluded a $1 trillion maintenance cost for the entire fleet over its lifespan, not accounting for inflation. The F-35 program office found that as of January 2014, costs for the F-35 fleet over a 53-year life cycle was $857 billion. Costs for the fighter have been dropping and accounted for the 22 percent life cycle drop since 2010. Lockheed stated that by 2019, pricing for the fifth-generation aircraft will be less than fourth-generation fighters. An F-35A in 2019 is expected to cost $85 million per unit complete with engines and full mission systems, inflation adjusted from $75 million in December 2013.
ENGINES:- The Pratt & Whitney F135 powers the F-35. An alternative engine, the General Electric/Rolls-Royce F136, was being developed until it was cancelled by its manufacturers in December 2011 for lack of funding from the Pentagon.The F135 and F136 engines are not designed to supercruise. However, the F-35 can briefly fly at Mach 1.2 for 150 miles without the use of an afterburner. The F135 is the second (radar) stealthy afterburning jet engine. Like the Pratt & Whitney F119 from which it was derived, the F135 has suffered afterburner pressure pulsations, or 'screech' at low altitude and high speed.The F-35 has a maximum speed of over Mach 1.6. With a maximum takeoff weight of 60,000 lb (27,000 kg), the Lightning II is considerably heavier than the lightweight fighters it replaces. The STOVL F-35B is outfitted with the Rolls-Royce LiftSystem, designed by Lockheed Martin and developed by Rolls-Royce. This system more resembles the German VJ 101D/E than the preceding STOVL Harrier Jump Jet and the Rolls-Royce Pegasus engine.The Lift System is composed of a lift fan, drive shaft, two roll posts and a "Three Bearing Swivel Module" (3BSM). The 3BSM is a thrust vectoring nozzle which allows the main engine exhaust to be deflected downward at the tail of the aircraft. The lift fan is near the front of the aircraft and provides a counterbalancing thrust using two counter-rotating blisks. It is powered by the engine's low-pressure (LP) turbine via a drive shaft and gearbox. Roll control during slow flight is achieved by diverting unheated engine bypass air through wing-mounted thrust nozzles called Roll Posts. F136 funding came at the expense of other program elements, impacting on unit costs. The F136 team stated their engine had a greater temperature margin, potentially critical for VTOL operations in hot, high altitude conditions. Pratt & Whitney tested higher thrust versions of the F135, partly in response to GE's statements that the F136 is capable of producing more thrust than the 43,000 lbf (190 kN) of early F135s. In testing, the F135 has demonstrated a maximum thrust of over 50,000 lbf (220 kN); making it the most powerful engine ever installed in a fighter aircraft as of 2010. It is much heavier than previous fighter engines; the Heavy Underway Replenishment system needed to transfer the F135 between ships is an unfunded USN requirement.Thermoelectric-powered sensors monitor turbine bearing health.At the end of May 2017 Pratt and Whitney announced the F135 Growth Option 1 had finished testing and was available for production. The upgrade requires the changing of the power module on older engines and can be seamlessly inserted into future production engines at a minimal increase in unit cost and no impact to delivery schedule. The Growth Option 1 offers a improvement of 6–10% thrust across the F-35 flight envelope while also getting a 5–6% fuel burn reduction.